School kids in Wales are being advised to cut down on using their mobile phones, in case of health problems.
At the moment there's no proof using a mobile phone does affect your health. But Wales's top doctor says there may be risks we don't yet know about.
Dr Tony Jewell says kids should text instead of call. He also advises keeping calls short - and using a hands-free kit if possible.
Leaflets are being sent out to schools across Wales.
Dr Ranj Singh gives Leah and Sonali his advice
Some people are worried that radio waves used by mobiles to send and receive calls and messages are linked to health problems. But there's currently no evidence of this.
Dr Jewell reckons more research needs to be done. "It is always better to be safe than sorry," he said.
Leah and Sonali spoke to Dr Ranj Singh, who advised: "I think it would be sensible to try and limit the amount of time you spend with the phone close to your head and yes texting may actually be safer [than calling]."